Euscorpius Occasional Publications in Scorpiology The Scorpion Sternum: Structure and Phylogeny (Scorpiones: Orthosterni)

Euscorpius is the first research publication completely devoted to scorpions (Arachnida: Scorpiones). Euscorpius takes advantage of the rapidly evolving medium of quick online publication, at the same time maintaining high research standards for the burgeoning field of scorpion science (scorpiology). Euscorpius is an expedient and viable medium for the publication of serious papers in scorpiology, including (but not limited to): systematics, evolution, ecology, biogeography, and general biology of scorpions. Review papers, descriptions of new taxa, faunistic surveys, lists of museum collections, and book reviews are welcome. Derivatio Nominis The name Euscorpius Thorell, 1876 refers to the most common genus of scorpions in the Mediterranean region and southern Europe (family Euscorpiidae). does not accept online texts as published work (Article 9.8); however, it accepts CD-ROM publications (Article 8). Euscorpius is produced in two identical versions: online (ISSN 1536-9307) and CD-ROM (ISSN 1536-9293). Only copies distributed on a CD-ROM from Euscorpius are considered published work in compliance with the ICZN, i.e. for the purposes of new names and new nomenclatural acts. All Euscorpius publications are distributed on a CD-ROM medium to the following museums/libraries: " My work is fascinating. To know that the organ, which you are observing , was seen by nobody before; to trace the proportions which nobody before you thought about; to submerge yourself into a won-drous, crystal world of a microscope, under a royal rule of silence limited by its own horizon; that dazzlingly white arena – all this is so exciting that I have no words ". Summary The structure of the sternum of all major Recent scorpion groups is analyzed in detail. Based on this analysis, two fundamental sternum types are identified, described and illustrated, type 1 and type 2. These sternum types are distinguished by criteria based on external and internal structural features. The sternum types described herein are offered as a replacement for the various characterizations used throughout the last 140 years which emphasize only gross overall shape and proportions. Phylogenetic and taxonomic ramifications of these new sternal types are discussed. The Carboniferous fossil scorpion Palaeopisthacanthus schucherti Petrunkevitch is assigned to sternum type 1. The type 1 sternum is also assigned to the three primitive Recent scorpion groups, the pseudochactids, the bu-thoids, and the chaerilids. Sternum type 2 is defined for the remaining scorpion groups, those complying with Type C orthobothriotaxy. Based on these assignments, sternum type 1 is considered primitive. Within these two …